1. Field of the Invention
This invention relates to curable epoxy resin compositions and electronic components. More particularly, this invention relates to curable epoxy resin compositions that have excellent storage stability prior to cure, excellent initial and durable adhesiveness, and that are well-suited for use as a protectant for-electronic components. The invention also relates to highly reliable electronic components that are coated with the cured product from the curable epoxy resin composition.
2. Description of the Related Art
Curable epoxy resin compositions provide cured products that have excellent electrical properties, for example, volume resistivity, breakdown strength, dielectric constant, and so forth, and as a result are used as protectants and coatings for electronic components. However, since these cured products are generally stiff and have poor fleability, when coated on an electronic component, they cause large internal stresses to be applied to the electronic component. This can result in cracking in the cured material and/or in destruction of the electronic component
To counter this, for example, Japanese Patent Publication Number Sho 62-27095 (1987) teaches a curable epoxy resin composition comprising the blend of curable epoxy resin and organopolysiloxane afforded by the hydrolysis and condensation of organosilane and bearing at least one epoxy-functional or amino-functional organic group and at least one hydroxyl group or hydrolyzable group, while Japanese Patent application Laid Open Number Sho 62-192423 (1987) teaches a curable epoxy resin composition comprising the blend of curable epoxy resin and epoxy-functional organopolysiloxane.
However, in the case of the curable epoxy resin composition proposed in Japanese Patent Publication Number Sho 62-27095, the final curable epoxy resin composition has a poor storage stability. The curable epoxy resin composition taught in Japanese Patent Application Laid Open Number Sho 62-192423 exhibits a poor initial and durable adhesiveness and thus performs poorly as a protectant for electronic components. Furthermore, these organopolysiloxanes are not compatible with curable epoxy resins, with the result that phase separation can occur during storage and the curable epoxy resin composition can suffer from a decline in transparency.
Moreover, electronic components coated with the cured products afforded by the aforementioned curable epoxy resin compositions suffer from the problem of poor reliability as manifested by a poor moisture resistance and heat resistance.
The inventors achieved the present invention as a result of extensive investigations into the problems described above.
In specific terms, an object of the present invention is to provide curable epoxy resin compositions that have excellent storage stability prior to cure, excellent initial and durable adhesiveness, and that are well-suited for use as protectants for electronic components. Another object of the present invention is to provide highly reliable electronic components that are coated with the cured product from the curable epoxy resin composition.